Generally, the drive train configuration in an electrically driven vehicle is the same configuration as in vehicles which have a central drive, comprising a combustion engine. Hereby, a drive device which comprises of an electric machine, a transmission, and a differential which is fixed to the chassis in a position in the center of the vehicle between the front wheels and the rear wheels; the drive torque is transferred like in conventional central drives via side shafts to the driven wheels. In such a configuration of the drive train, the chassis concept is mostly maintained, wherein only modifications in the aggregate bearings and auxiliary frames are required.
In an electrically driven or rather drivable vehicle which comprises a central drive, accommodating the battery represents a significant construction modification. It is known hereby that the battery needs to be integrated, for instance under the back seat or in an area which is usually occupied by the transmission duct in central drives having a combustion engine.
Also, electric drives that are arranged near the wheels are known in the state-of-the-art, wherein near the wheel means a drive in the broader sense which has one or several electric motors for each driven wheel of a vehicle. Therefore, vehicles are known which have two or more driven wheels which have a corresponding number of drives, meaning two or more. Hereby each electric motor can precisely drive one drive wheel.
In addition, known in the state of the art are electric drives arranged close to the wheel so as to drive a driven wheel for electrically driven vehicles which are integrated into the chassis of the vehicle whereby, depending on the number of driven wheels of the vehicle, either two or four electric drives are provided.
Wherein, the electric drives can be positioned fixed to the wheel carrier; in this case, the electric drive swings directly with the respective wheel and the unsuspended mass is directly influenced by the drive.
Another possibility for positioning, the electric drives which are close to the wheel can be fixed in position. Hereby, the electric drives are moved from the center of the vehicle towards the wheels. The drives are, however, still attached to the chassis structure and therefore do not influence the unsuspended masses.
The electric drives can also be positioned at suspension rods, whereby they are attached in this case at the chassis suspension rods, for instance at the torsion rods. In this concept, the unsuspended mass is reduced by positioning the electric drives close to the chassis-fixed connection points of the suspension rod.
Known through the DE 10 2007 039 059 A1 by the applicant is a driven vehicle axle, designed as a torsion rod axle, in which each wheel of the axle has an electric motor assigned to it which is positioned with the rotational axis in the longitudinal direction of the vehicle, whereby its housing represents a part of the longitudinal swing part of the torsion rod.
The drives which are close to the wheel can be utilized in vehicles with an all-wheel, front, or rear drive, whereby the type of axles of the driven vehicle axles can be conventional axle types, such as for instance strut axles or double wishbone axles. In addition the drives close to the wheel can be integrated with the wheel integrated chassis.
Also, the electric drives which are close to the wheel can have a transmission.
Known through WO 2008/017945 A1 is a drive device, which can be integrated into a wheel of a vehicle, to drive the wheel where the device comprises of an electric motor and a transmission device, wherein the transmission device comprises a spur gear transmission and a planetary transmission which are connected in series. Hereby, the planetary transmission is positioned, viewed in the flow of force direction in traction operation, at the output side of the spur gear transmission.
The use of electric drives close to the wheel for driving a wheel of a driven axle results, in an advantageous manner, in a vehicle configuration with a high flexibility, because of the elimination of the central drive in the center of the vehicle creates, and new degrees of freedom in the vehicle design, in particular during the design of the interior of the vehicle, the battery accommodation, and the crash safety.
In addition, drives torques can be generated at individual wheels through electric drives near the wheel, whereby functions such as torque vectoring, ESP, ABS, ASR, etc. can be realized in a simple way. Through the fast and accurate control of electric drives, these functions can be optimized in comparison to the traditional, brake based control systems.